POS1445 EARLY DETECTION OF AXIAL PSORIATIC ARTHRITIS IN PATIENTS WITH PSORIASIS: A PROSPECTIVE, MULTICENTER STUDY.
Authors: F. Proft, S. Lüders, T. Hunter, G. Luna, V. Rios Rodriguez, M. Protopopov, K. Meier, G. Kokolakis, K. Ghoreschi, D. Poddubnyy
Journal: Annals of the Rheumatic Diseases (2022)

Background In the absence of reliable serological and/or imaging biomarkers that can support an early diagnosis of psoriatic arthritis (PsA) in patients with psoriasis (PsO), and considering the known diagnostic delay there is a need for screening tools for detection of early PsA. While different validated screening/referral tools focusing on peripheral manifestations of PsA exist, validated referral algorithms for PsA with axial involvement (also referred to as axial PsA - axPsA) are still missing. Objectives In this prospective, multicenter study we applied a dermatologist-centered screening tool and a structured rheumatologic examination including magnetic resonance imaging (MRI) of sacroiliac joints (SIJs) and spine to detect axPsA in patients with psoriasis (PsO). Methods Patients with PsO were systematically screened by their dermatologist for eligibility for referral to a rheumatology clinic. Eligible patients were ≥ 18 years with a confirmed diagnosis of PsO who reported having chronic back pain (≥ 3 months) with onset prior to 45 years of age and who had not been treated with any biologic or targeted synthetic DMARD 12 weeks prior to screening. For those patients who qualified for referral a rheumatologic investigation including clinical, laboratory and genetic assessments as well as imaging with conventional radiography and MRI of sacroiliac joints and spine was performed. The primary outcome of the study was the proportion of patients diagnosed with axPsA among all referred PsO patients. Results In total 355 patients were screened at 14 dermatology sites, of whom 151 (42.5%) qualified for referral to rheumatology clinic and 100 (28.2%) were seen by a rheumatologist. The diagnosis of axPsA was confirmed in 14 patients (3/14 with both, axial and peripheral involvement) and the diagnosis of peripheral PsA (pPsA) without axial involvement was made in five patients. The ASAS classification criteria for axSpA were fulfilled in nine (64.3%) of the patients diagnosed with axPsA. All but one patient diagnosed with PsA (13/14 with axPsA and 5/5 with pPsA) fulfilled the CASPAR criteria for PsA. Patient characteristics are presented in Table 1. All patients diagnosed with axPsA had active inflammatory and/or structural (post)inflammatory changes in the sacroiliac joints and/or spine on imaging. In five patients (35.7%), MRI changes indicative of axial involvement were found only in the spine as illustrated in Figure 1. Table 1. Clinical characteristics of all referred patients with PsO and suspicion of axSpA. Patient characteristic pPsA (N=5) axPsA (N=14) No PsA (N=81) p-value 1 Age (years) – Mean (SD) 42.8 (9.0) 46.2 (13.6) 45.7 (13.3) 0.883 Female – n (%) 2 (40.0) 9 (64.3) 45 (55.6) 0.543 PASI – Mean (SD) 3.3 (2.1) 4.3 (4.9) 4.0 (4.5) 0.971 Inflammatory back pain – n (%) 5 (100.0) 8 (57.1) 36 (44.4) 0.379 HLA-B27 positive – n (%) 0 4 (28.6) 12 (14.8) 0.204 Elevated CRP (&gt;5 mg/L) – n (%) 1 (20.0) 5 (35.7) 11 (13.6) 0.041 Peripheral arthritis, current (last 7 days) – n (%) 5 (100.0) 3 (21.4) 3 (3.7) 0.012 Radiographic sacroiliitis as per mNY criteria – n (%) 0 4 (28.6) 1 (1.2) &lt;0.001 Active inflammation, sacroiliac joint (MRI) – n (%) 0 8 (57.1) 0 &lt;0.001 Structural (post)inflammatory changes, sacroiliac joint (MRI) – n (%) 0 8 (57.1) 0 &lt;0.001 Active inflammation, spine (MRI) – n (%) 0 13 (92.9) 0 &lt;0.001 Structural (post)inflammatory changes, spine (MRI) – n (%) 0 8 (57.1) 0 &lt;0.001 1 Statistically significant differences between the axPsA and No PsA groups of patients were determined by using Mann–Whitney U test for continuous data and Chi-square test for categorical data Figure 1. Imaging features of axial involvement in PsO patients diagnosed with axPsA Conclusion Our study revealed that applying a dermatologist-centered screening tool may be useful for the early detection of patients with a high probability of PsA (and specifically axPsA) in PsO patients. Given the high prevalence of isolated spinal involvement (without SIJs), imaging of the entire axial skeleton may be required as a part of diagnostic procedure in patients with suspected axPsA. Acknowledgements Caroline Höppner, Rebecca Bolce, David Sandoval, Hagen Russ, Burkhard Muche, Judith Rademacher, Hildrun Haibel, Laura Spiller and all cooperating dermatologists. Disclosure of Interests Fabian Proft: None declared, Susanne Lüders: None declared, Theresa Hunter Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, Gustavo Luna: None declared, Valeria Rios Rodriguez: None declared, Mikhail Protopopov: None declared, Katharina Meier: None declared, Georgios Kokolakis: None declared, Kamran Ghoreschi: None declared, Denis Poddubnyy: None declared